Simultaneous coupling of fluidized granular activated carbon (GAC) and powdered activated carbon (PAC) with ultrafiltration process: A promising synergistic alternative for water treatment

Abstract

Ultrafiltration (UF) has been extensively employed in current water treatment practice, during which limited removal for soluble contaminants and membrane fouling remain two perennial hurdles to efficient operation. This study proposed a promising approach by simultaneous coupling of fluidized granular activated carbon (GAC) and PAC with UF process, whereby PAC was responsible for improving effluent quality, and fluidized GAC was targeted for mitigating UF fouling and PAC deposition. The operational performance of such integrated GAC-PAC-UF system was systemically evaluated in a lab-scale setup. The results showed that fluidized GAC particles with larger size appeared highly effective in removing PAC deposition and fouling formed by surface water. PAC addition improved the effluent quality mainly by adsorbing humic acid-like substances. More importantly, energy consumption by GAC fluidization was found to be at least an order-of-magnitude lower than conventional fouling control methods employed in UF. Furthermore, redundancy analysis revealed that the key mechanism for UF fouling mitigation was tied to GAC particle momentum, whereas inorganic fouling mitigation was mostly achieved by GAC-induced liquid turbulence. It is expected that such integrated GAC-PAC-UF process proposed should be technically feasible and economically viable, potentially achieving high permeate quality and reducing membrane fouling with limited energy requirement.